Motorized potentiometer



July 21, 1970 0. J. RUSSO MOTORIZED POTENTIOMETER 2 Sheets-Sheet 1 FiledJuly 1, 1968 I INVENTOR Jaw/we J Pz/sso WW/M2 ATTORNEYS July 21, 1970 D.J. RUSSO MOTORIZED POTENTIOMETER 2 Sheets-Sheet 2 Filed Julyl, 1968INVENTO R )ww/wc (ma/55a ATTORNEYS United States Patent 3,521,095MOTORIZED POTENTIOMETER Dominic J. Russo, Yankton, S. Dak., assignor toDale Electronics, Inc., Columbus, Nebr., a corporation of Nebraska FiledJuly 1, 1968, Ser. No. 741,554 Int. Cl. H02k 7/10 US. Cl. 310-83 4Claims ABSTRACT OF THE DISCLOSURE A motor-potentiometer combination inwhich the motor drive can be disconnected from the potentiometer whenmanual operation of the potentiometer is desired. The magnetic core ofthe rear pole piece assembly is integral and functions as a solenoidplunger and when electrically actuated moves the normally disconnectedmotor gear train and potentiometer gear train into engagement. The corehas an elongated non-magnetic extension. The latter together with themagnetic core and rotor shaft are mounted along the central axis of thehousing.

This invention relates to a motorized potentiometer in which the motorengages the gear train only when the motor is energized. When the motoris deenergized the potentiometer is free of the motor and its gear trainand is adaptable for manual adjustment.

It is an object of the present invention to form the stator and aportion of the core piece into one movable part to permit movementwithin the fixed stator, and thereby utilize the core as a solenoidplunger to slide a pinion of the motor into driving engagement with thepotentiometer. When the core of the pole piece is moved in the oppositedirection the pinion of the motor is withdrawn from driving engagementwith the potentiometer, and the latter may be adjusted manually.

Another object of the present invention is to provide the solenoidplunger with a metallic ring, preferably of copper, to create a shadedpole effect which results in a more efficient motor.

It is still another object of the present invention to provide amotorized potentiometer having fewer parts than previous constructions,thereby making the same relatively inexpensive to manufacture and havinga higher degree of reliability.

It is a further object of the present invention to-have a completemagnetic path between the core and pole pieces. This constructionreduces the magnetic losses in the motor thereby making the motor morepowerful and permitting the motor to run cooler.

The invention is illustrated by way of example in the accompanyingdrawings which form part of the application and in which:

FIG. 1 is a cross-sectional view of motor-potentiometer combinationconstructed in accordance with the teachings of the present invention;and with the motor gear train disengaged from the potentiometer geartrain;

FIG. 2 is a cross-sectional view of the motor-potentiometer combinationsimilar to the view shown in FIG. 1, but with certain parts removed, andwith the motor gear train engaged with the potentiometer gear train; and

FIG. 3 is a transverse section taken along the lines 3-3 of FIG. 1.

Referring to the drawings, the present motorpotentiometer combinationcomprises a motor housing 10 and a potentiometer and gear train casing12 which are co-extensive. Mounted in the motor housing 10 are stators14 and 16A and 16B and a rotor 18. The coils of the stators 14 and 16are shown as A and B respectively. In addition, electrical terminals forthe stators A and B are designated by reference numerals 15 and 17respectively. A cylindrical magnetic core 20 has a yoke portion 22attached to it and forms the rear pole piece assembly. Core 20 is formedin a manner to permit it to move within the fixed stator 14 parallel tothe longitudinal axis of the motor and in the directions of thedouble-headed arrow C. The cylindrical magnetic core which functions inthe manner of a solenoid plunger is provided with a non-magneticpin-like extension 24 which also extends parallel to the longitudinalaxis of the motor. Mounted co-axially with non-magnetic extension 24 isthe slidable rotor shaft 26. The latter also extends through a bore 28in the stator 16 and is freely shiftable therein. An abutment member 30is located in the center of the two poles of the stator 14 and partthereof. Mounted on the non-magnetic extension 24 between the slidablemagnetic core 20 and the abutment member 30 is a non-magnetic,anti-shick washer 58. A metallic ring 3-2 such as copper creates ashaded pole effect for the motor, and thereby makes the same a morepowerful, smoother running motor. Attached to the end of the rotor shaft26 remote from extension 24 are motor gears 34, 36, 38 and 40. Gear 40has coupling pins 42 projecting from a front surface thereof which areadapted to be engaged in adjacent openings 44 arranged circularly on apart 46 of the gear 48 of the gear train of the potentiometer P. Thepotentiometer gear train also includes gears 50, 52 and 54 respectively.

As clearly seen in FIGS. 1 and 2, the motor is disconnected from thepotentiometer P in FIG. 1 and connected to the potentiometer as shown inFIG. 2. In the latter event, the cylindrical magnetic core 20 has slidto the right by magnetic flux produced upon the application of voltagesto the coil A of the stator 14. When this occurs, the non-magneticextension 24 pushes the rotor shaft 26 also to the right causing thepins 42 of the gear 40 to seat in the adjacent holes 44 of part 46 ofgear 48 in the potentiometer gear train. Thus, the motor is drivinglyconnected to the potentiometer P. A spring 56 engages at one end thepart 46 and engages at the other end the gear 42. Therefore, the spring56 normally urges the rotor shaft 26, the extension 24 and thecylindrical magnetic core 20 to the left whereby the assembly normallyassumes the position shown in FIG. 1 with the motor and potentiometer Pdisengaged.

It should be noted that the present motor-potentiometer combination hasthe desirable attribute of permitting the potentiometer to be manuallyoperated without the drag of the rotor shaft and the motor gear train.In addition, the present construction, having fewer parts than otherknown structures, is less expensive to manufacture and more reliable inoperation.

What is claimed is:

1. A motor-potentiometer combination, wherein both said motor andpotentiometer have associated gear trains comprising; a housing, a rotorand a stator mounted in said housing; a rear pole piece assembly in saidhousing having a core; an elongated non-magnetic extension mounted onsaid core substantially co-axially therewith and slidably movable withsaid core along the longitudinal axis of said housing when said statoris electrically actuated; a rotor shaft mounted for sliding movement insaid housing, said elongated extension and rotor shaft abutting eachother in an end-to-end relationship; a pinion on the other end of saidrotor shaft having means for drivingly engaging the gear trainassociated with said potentiometer when said core is moved in onedirection and disengaging said gear train associated with saidpotentiometer when said core is moved in the opposite direction; saidmagnetic core of the rear pole piece assembly, said elongatednon-magnetic extension, and said rotor shaft being mounted along thecentral axis of said housing; and a spring positioned between saidpotentiometer gear train and said motor gear train normally urging themeans for drivingly engaging the potentiometer gear train out ofengagement with the latter.

' 2. A motor-potentiometer combination as claimed in claim 1 furthercomprising a metallic ring mounted on the core of said rear pole pieceand adjacent to said stator for creating a shaded pole effect for saidmotor.

3. A motor-potentiometer combination as claimed in claim 1 wherein saidcore and rear pole piece are integral. 4. A motor-potentiometercombination as claimed in claim 1 wherein said rear pole piece assemblyis provided with an attached rear pole piece and core having a completemagnetic path between said core and said pole pieces.

References Cited UNITED STATES PATENTS MILTON O. HIRSHFIELD, PrimaryExaminer -R. SKUDY, Assistant Examiner US. Cl. X.R. 310-78; 89

